Input Validation / File Path Manipulation

Description

File path manipulation is a type of input validation vulnerability that occurs when user input is not properly sanitized, allowing malicious users to modify the file paths used by a web application or API. This vulnerability is classified in the Common Weakness Enumeration (CWE) directory as CWE-22, and is considered an important security risk by the Open Web Application Security Project (OWASP) Testing Guide.

Risk

File path manipulation can have serious security implications, as malicious users can potentially gain access to files and directories that are outside the application's control. This could lead to unauthorized changes, data leakage, or even complete system compromise, making it essential for developers to address this vulnerability.

Solution

Input validation is the best way to prevent file path manipulation. This involves ensuring that user input is checked against a list of acceptable characters and values. For example, if a web application only allows users to access specific directories, then the application should validate that the input only contains the characters used to access those directories. Additionally, developers should be aware of any potential attack vectors, such as URL redirection and path traversal, which could be used to bypass input validation checks.

Example

The following code snippet is an example of a vulnerable application that is vulnerable to file path manipulation attacks.

String filePath = request.getParameter("filePath");

File file = new File(filePath);

In this example, the application is taking user input from the parameter filePath and using it to create a File object. However, this code does not validate the user input, meaning that an attacker could supply a malicious file path and gain access to files outside the application's control.